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1.
To examine the reliability for peak responses of oxygen consumption (VO2peak) in relative (ml · kg-1 · min-1) and absolute (L/min-1) measures, as well as peak heart rate (HRpeak) during deep water running (DWR), 26 participants (12 women, 14 men) completed two DWR maximal graded exercise tests. To estimate the validity of the peak responses during DWR, a comparison to a treadmill running (TMR) graded exercise test (GXT) was completed. Test order was randomized. The DWR GXT utilized a system of weights and pulleys to increase intensity of exercise. Reliability of the DWR test for the total group was estimated using a repeated measures one-way analysis of variance (ANOVA) for VO2peak (ml · kg-1 · min-1, R = .96; L/min-1, R = .97) and HRpeak (R = .90). There were no significant differences (p > .05) between the two DWR tests for men or women for the means of VO2peak in relative units (men: 50.5 vs. 52.0 ml · kg-1 · min-1; women: 37.1 vs. 36.8 ml · kg-1 · min-1), or absolute units (men: 4.1 vs. 4.1 L/min-1; women: 2.2 vs. 2.2 L/min-1), or HR (men: 174 vs. 175 beats per minute (bpm); women: 181 vs. 183 bpm). There was a significant correlation between the average of the two DWR tests and TMR for the total group for VO2peak for relative (r = .88, p = .001) and absolute (r = .93, p = .001) measures as well as HRpeak (r = .64, p = .001). Peak responses during the DWR protocol were judged to be reliable. Also, the correlation for the variables between DWR and TMR indicates a positive relation between peak responses. The correlation suggests validity of predicting TMR peak responses from DWR peak responses; however, this conclusion may be questionable due to the low sample size and the large systemic differences between tests. Finally, HRpeak and VO2peak were lower during DWR than TMR for both men and women.  相似文献   

2.
The first purpose of this study was to determine the norm-referenced predictive validity of maximal oxygen consumption (VO2) max estimated from the progressive aerobic cardiovascular endurance run (PACER, FITNESSGRAM®; Cooper Institute for Aerobic Research, Dallas, TX) performance by 3 separate formulas: the Leger, Mercier, Gadoury, and Lambert (1988) 8- to 19-year-old equation; the Leger et al. adult equation; and the Ramsbottom, Brewer, and Williams (1988) equation. Norm-referenced intraclass stability reliability coefficients (n = 19) were determined to be .96 for PACER and estimated VO2 max values. Only the VO2 max values estimated from the Leger et al. adult equation (47.29 ± 7.02 vs. 50.45 ± 8.01 rnL · kg-1 · min-1 measured; p < .0001) were shown to be valid (r = .82; standard error of estimate [SEE] = 4.59; Error = 5.58; percentage of participants whose measured VO2 max fell within ± 4.5 mL · kg-1 · min-1 of estimated VO2 max = 59.7; N = 60 female participants ± 59 male participants). The second purpose was to cross-validate the Cureton, Sloninger, O'Bannon, Black, and McCormack (1995) equation for the estimation of VO2 max from the one-mile run (1-MR). The results (estimated VO2 max = 48.06 ± 6.57 vs. 50.45 ± 8.01 rnL · kg-1 · min-1 measured; p < .0001; r= .82; SEE = 4.53; Error = 5.27; percentage = 61.7; N = 50 female ± 44 male participants) indicated a norm-referencedpredictive validity similar to the Leger et al. adult PACER equation. There was no significant difference between the VO2max estimated by the Leger et al. 8- to 19-year-old and the Cureton et al. equations. Correlations between 1-MR time and measured VO2 max (r = .78) and PACER laps and measured 90, maw (r = 33) supported norm-referenced concurrent validity in this population. The third purpose was to determine the criterion-referenced reliability and validity of the PACER and 1-MR. Criterion-referenced reliability indicated a proportion of agreement (P) of .95 and a modified Kappa (K) of .90 for PACER laps and estimated VO2 max. A .88 proportion of correct classification decisions (c) with a phi coefficient (?) of .08 was determined for criterion-referenced validity of the Leger et al. adult equation. Comparable validity coefficients for the Cureton et al. equation were c = .97 and ? = .65. Criterion-referenced equivalence reliability (P) was .90 with a Kq of .80 for the 1-MR and PACER. It was concluded that (a) the Leger et al. (1988) adult equation is the preferred equation to use to estimate VO2 max from PACER scores for college aged individuals; (b) the Cureton et al. (1995) equation is valid for estimating VO2 max in college students from the 1-MR; and (c) the FITNESSGRAM® (Cooper Institute for Aerobics Research, 1992) criterion-referenced standards using data from the Cureton et al. and Leger et al. adult equations were both reliable and valid in this population. The 1-MR and the PACER may be used interchangeably in this age group to assess cardiovascular fitness either from performance scores or estimated VO2 max if the Leger et al. adult equation is used for PACER VO2 max prediction.  相似文献   

3.
This study sought to develop a modified submaximal cycle ergometer test designed to predict maximal oxygen consumption (VO2max) obtained on a treadmill. Volunteers (N = 156; women = 80, men = 76) with ages from 18 to 39 years old successfully performed a submaximal cycle protocol on a stationary cycle ergometer and a maximal graded exercise test (GXT) on a treadmill. Open circuit calorimetry was used during the GXT to measure VO2max. Multiple linear regression resulted in the following prediction equation: VO2max = 85.447 + 9.104 χSex (0 = women; 1 = men) - 0.2676 χAge (year) - 0.4150 χBody Mass (kg) + 0.1317 χPower Output (W) - 0.1615 χHeart Rate (bpm), which had acceptable validity (r = .88, standard error of estimate [SEE] = 3.12 ml· kg-1 · min-1). Selected participants (n = 34) performed the submaximal cycle ergometer test twice (within a 5-day period), yielding a test-retest intraclass reliability coefficient of r = .95 for VO2max estimations across days. The reliability of VO2max estimates for women (r = .93) was greater than that for men (r = .74). Cross-validation results were also acceptable using predicted residual sum of squares (PRESS; rPRESS = .87, SEEPRESS = 3.24 ml · kg-1 min-1), which suggests that the new equation should yield acceptable accuracy when it is applied to a similar, but independent sample of adults. In summary, the modified cycle ergometer test developed in this study yields relatively accurate estimates of treadmill VO2max in young adults, requires only a moderate level of exertion, and appears to be a convenient and time-efficient means of estimating cardiorespiratory fitness.  相似文献   

4.
The purpose of this study was to develop a multiple linear regression model to predict treadmill VO2max scores using both exercise and non-exercise data. One hundred five college-aged participants (53 male, 52 female) successfully completed a submaximal cycle ergometer test and a maximal graded exercise test on a motorized treadmill. The submaximal cycle protocol required participants to achieve a steady-state heart rate equal to at least 70% of age-predicted maximum heart rate (220-age), while the maximal treadmill graded exercise test required participants to exercise to volitional fatigue. Relevant submaximal cycle ergometer test data included a mean (±SD) ending steady-state heart rate and ending workrate equal to 164.2 ± 13.0 bpm and 115.3 ± 27.0 watts, respectively. Relevant non-exercise data included a mean (±SD) body mass (kg), perceived functional ability score, and physical activity rating score of 74.2 ± 15.1, 15.7 ± 4.3, and 4.7 ± 2.1, respectively. Multiple linear regression was used to generate the following prediction of (R = .91, standard error of estimates (SEE) = 3.36 ml·kg?1·min?1): VO2max = 54.513 + 9.752 (gender, 1 = male, 0 = female) – .297 (body mass, kg) + .739 (perceived functional ability, 2–26) + .077 (work rate, watts) – .072 (steady-state heart rate). Each predictor variable was statistically significant (p < .05) with beta weights for gender, body mass, perceived functional ability, exercise workrate, and steady-state heart rate equal to .594, –.544, .388, .305, and –.116, respectively. The predicted residual sums of squares (PRESS) statistics reflected minimal shrinkage (RPRESS = .90, SEEPRESS = 3.56 ml·kg?1·min?1) for the multiple linear regression model. In summary, the submaximal cycle ergometer protocol and accompanying prediction model yield relatively accurate VO2max estimates in healthy college-aged participants using both exercise and non-exercise data.  相似文献   

5.
The purpose of this study was to provide a more detailed analysis of performance in cross-country skiing by combining findings from a differential global positioning system (dGPS), metabolic gas measurements, speed in different sections of a ski-course and treadmill threshold data. Ten male skiers participated in a freestyle skiing field test (5.6?km), which was performed with dGPS and metabolic gas measurements. A treadmill running threshold test was also performed and the following parameters were derived: anaerobic threshold, threshold of decompensated metabolic acidosis, respiratory exchange ratio = 1, onset of blood lactate accumulation and peak oxygen uptake ([Vdot]O2peak). The combined dGPS and metabolic gas measurements made detailed analysis of performance possible. The strongest correlations between the treadmill data and final skiing field test time were for [Vdot]O2peak (l?·?min?1), respiratory exchange ratio = 1 (l?·?min?1) and onset of blood lactate accumulation (l?·?min?1) (r = ?0.644 to ??0.750). However, all treadmill test data displayed stronger associations with speed in different stretches of the course than with final time, which stresses the value of a detailed analysis of performance in cross-country skiing. Mean oxygen uptake ([Vdot]O2) in a particular stretch in relation to speed in the same stretch displayed its strongest correlation coefficients in most stretches when [Vdot]O2 was presented in units litres per minute, rather than when [Vdot]O2 was normalized to body mass (ml?·?kg?1?·?min?1 and ml?·?min?1?·?kg?2/3). This suggests that heavy cross-country skiers have an advantage over their lighter counterparts. In one steep uphill stretch, however, [Vdot]O2 (ml?·?min?1?·?kg?2/3) displayed the strongest association with speed, suggesting that in steep uphill sections light skiers could have an advantage over heavier skiers.  相似文献   

6.
This study compares test-retest reliability and peak exercise responses from ramp-incremented (RAMP) and maximal perceptually-regulated (PRETmax) exercise tests during arm crank exercise in individuals reliant on manual wheelchair propulsion (MWP). Ten untrained participants completed four trials over 2-weeks (two RAMP (0–40 W + 5–10 W · min?1) trials and two PRETmax. PRETmax consisted of five, 2-min stages performed at Ratings of Perceived Exertion (RPE) 11, 13, 15, 17 and 20). Participants freely changed the power output to match the required RPE. Gas exchange variables, heart rate, power output, RPE and affect were determined throughout trials. The V?O2peak from RAMP (14.8 ± 5.5 ml · kg?1 · min?1) and PRETmax (13.9 ± 5.2 ml · kg?1 · min?1) trials were not different (P = 0.08). Measurement error was 1.7 and 2.2 ml · kg?1 · min?1 and coefficient of variation 5.9% and 8.1% for measuring V?O2peak from RAMP and PRETmax, respectively. Affect was more positive at RPE 13 (P = 0.02), 15 (P = 0.01) and 17 (P = 0.01) during PRETmax. Findings suggest that PRETmax can be used to measure V?O2peak in participants reliant on MWP and leads to a more positive affective response compared to RAMP.  相似文献   

7.
The purposes of this study were to determine (a) the test-retest reliability of cardiorespiratory responses to exercise performed on the StairMaster 4000PT® (SM-4000) and (b) the validity of the SM-4000 for estimating oxygen consumption (VO2) based on final SM-4000 stepping speed. Sixty-one participants (30 men, 31 women) performed two graded exercise tests separated by 6 to 8 days. Participants began stepping at the lowest intensity stage (26 steps/min-1) and intensity was increased by 1 stage each minute (8-9 steps/min-1) until volitional exhaustion or until maximal stepping speed was reached (138 steps/min-1). SM-4000-generated VO2 (SMVO2), measured VO2 (MVO2), heart rate, respiratory exchange ratio, and ratings of perceived exertion were measured during each minute of the test. Intraclass (Rxx') and interclass (rxx') reliability coefficients were high for both men and women for all variables (Rxx' ≥ .91 and rxx' ≥ .83 for men, Rxx' ≥ .92 and rxx' ≥ .88 for women). Estimated reliability coefficients from a single administration of the test based on intraclass reliability were high for all variables for both sexes (Rxx' ≥ .83). Standard errors of measurement for SMVO2 and MVO2 indicate these variables are reproducible within small ranges of variation. High concurrent validity coefficients for men and women (rxx' = .87 and .92, respectively) and small Standard Errors of Estimate (2.3 and 2.2 ml middot; kg-1 min-1, respectively), indicate a high correlation exists between SMVO2 and MVO2. However, significant differences between group means for SMVO2 and MVO2 occurred for men (44.3 vs. 37.9 ml · kg-1 · min-1, p < .0001) and women (41.3 vs. 33.2 ml · kg-1 · min -1, p < .0001). This, coupled with large total error values (6.9 and 8.5 ml · kg -1 · min-1 for...  相似文献   

8.
Abstract

This study was conducted to determine if the Polar FT40 could accurately track changes in maximal oxygen consumption (VO2max) in a group of female soccer players. Predicted VO2max (pVO2max) via the Polar FT40 and observed VO2max (aVO2max) from a maximal exercise test on a treadmill were determined for members of a collegiate soccer team (n = 20) before and following an 8-week endurance training protocol. Predicted (VO2max and aVO2max measures were compared at baseline and within 1 week post-training. Change values (i.e., the difference between pre to post) for each variable were also determined and compared. There was a significant difference in aVO2max (pre = 43.6 ± 2.4 ml · kg · min?1, post = 46.2 ± 2.4 ml · kg · min?1, P < 0.001) and pVO2max (pre = 47.3 ± 5.3 ml · kg · min?1, post = 49.7 ± 6.2 ml · kg · min?1, P = 0.009) following training. However, predicted values were significantly greater at each time point compared to observed values (P < 0.001 at pre and P = 0.008 at post). Furthermore, there was a weak correlation between the change in aVO2max and the change in pVO2max (r = 0.18, P = 0.45). The Polar FT40 does not appear to be a valid method for predicting changes in individual VO2max following 8 weeks of endurance training in female collegiate soccer players.  相似文献   

9.
Carbohydrate (CHO) availability during endurance exercise seems to attenuate exercise-induced perturbations of cellular homeostasis and might consequently diminish the stimulus for training adaptation. Therefore, a negative effect of CHO intake on endurance training efficacy seems plausible. This study aimed to test the influence of carbohydrate intake on the efficacy of an endurance training program on previously untrained healthy adults. A randomized cross-over trial (8-week wash-out period) was conducted in 23 men and women with two 8-week training periods (with vs. without intake of 50g glucose before each training bout). Training intervention consisted of 4x45 min running/walking sessions/week at 70% of heart rate reserve. Exhaustive, ramp-shaped exercise tests with gas exchange measurements were conducted before and after each training period. Outcome measures were maximum oxygen uptake (VO2max) and ventilatory anaerobic threshold (VT). VO2max and VT increased after training regardless of CHO intake (VO2max: Non-CHO 2.6 ± 3.0 ml*min?1*kg?1 p = 0.004; CHO 1.4 ± 2.5 ml*min?1*kg?1 p = 0.049; VT: Non-CHO 4.2 ± 4.2 ml*min?1*kg?1 p < 0.001; CHO 3.0 ± 4.2 ml*min?1*kg?1 p = 0.003). The 95% confidence interval (CI) for the difference between conditions was between +0.1 and +2.1 ml*min?1*kg?1 for VO2max and between ?1.2 and +3.1 for VT. It is concluded that carbohydrate intake could potentially impair the efficacy of an endurance training program.  相似文献   

10.
In this study, we investigated the accuracy of self-pulse counting as a method of measuring exercise intensity in middle school-age boys. Sixty-three boys (age = 12.7 ± 1.0 years; stature = 157.7 ± 7.0 cm; mass = 49.5 ± 12.4 kg; body fat = 19.1 ± 11.8%; VO2peak = 52.8 ± 7.8 ml · kg · min-1) from 15 different schools were instructed in carotid pulse palpation. Participants were instructed to use 2 fingers of either hand, allowed to palpate the carotid artery on either side of the neck, and given the opportunity to briefly practice. Following self-pulse counting instructions and practice, participants were connected to a telemetry system using a single-lead electrocardiogram recording (CM5). With instructions to walk as fast as possible, they then completed a 720-m shuttle walk on an 18-m course. Postwalk heart rates (HRs) were simultaneously measured via telemetry and self-pulse palpation for 15 sec, with results converted to beats (b)· min-1. The mean postexercise HR, as determined by telemetry and self-pulse palpation of the carotid artery, were 165.1 ± 22.0 and 143.6 ± 31.3 b · min-1, respectively. The mean paired difference was 21.6 ± 23.3 b · min-1. A paired t test revealed significant underreporting of postexercise HR by self-pulse palpation, t(62) = 7.4, p < .001. In total, 56 of the 63 boys reported pulse counts lower than their actual electrocardiogram recordings. We conclude that self-reported postexercise pulse counts are inaccurate in middle school-age boys. If accuracy is paramount, we recommend that a monitoring device should be used or that it be confirmed that individual children can accurately count their own postexercise pulse.  相似文献   

11.
This study was designed to develop a single-stage submaximal treadmill jogging (TMJ) test to predict VO2max in fit adults. Participants (N?=?400; men?=?250 and women?=?150), ages 18 to 40 years, successfully completed a maximal graded exercise test (GXT) at 1 of 3 laboratories to determine VO2max. The TMJ test was completed during the first 2 stages of the GXT. Following 3 min of walking (Stage 1), participants achieved a steady-state heart rate (HR) while exercising at a comfortable self-selected submaximal jogging speed at level grade (Stage 2). Gender, age, body mass, steady-state HR, and jogging speed (mph) were included as independent variables in the following multiple linear regression model to predict VO2max (R?=?0.91, standard error of estimate [SEE]?=?2.52 mL?·?kg?1?·?min?1): VO2max (mL?·?kg?1?·?min?1)?=?58.687?+?(7.520 × Gender; 0?=?woman and 1?=?man)?+?(4.334 × mph) ? (0.211 × kg) ? (0.148 × HR) ? (0.107 × Age). Based on the predicted residual sum of squares (PRESS) statistics (RPRESS?=?0.91, SEE PRESS?=?2.54 mL?·?kg?1?·?min?1) and small total error (TE; 2.50 mL?·?kg?1?·?min?1; 5.3% of VO2max) and constant error (CE; ?0.008 mL?·?kg?1?·?min?1) terms, this new prediction equation displays minimal shrinkage. It should also demonstrate similar accuracy when it is applied to other samples that include participants of comparable age, body mass, and aerobic fitness level. This simple TMJ test and its corresponding regression model provides a relatively safe, convenient, and accurate way to predict VO2max in fit adults, ages 18 to 40 years.  相似文献   

12.
Abstract

We compared cardiorespiratory responses to exercise on an underwater treadmill (UTM) and land treadmill (LTM) and derived an equation to estimate oxygen consumption (VO2) during UTM exercise. Fifty-five men and women completed one LTM and five UTM exercise sessions on separate days. The UTM sessions consisted of chest-deep immersion, with 0, 25, 50, 75, and 100% water-jet resistance. All session treadmill velocities increased every 3 min from 53.6 to 187.8 m·min-1. Cardiorespiratory responses were similar between LTM and UTM when jet resistance for UTM was ≥ 50%. Using multiple regression analysis, weight-relative VO2 could be estimated as: VO2 (mLO2·kg-1·min-1) = 0.19248 · height (cm) + 0.17422 · jet resistance (% max) + 0.14092 · velocity (m·min-1) - 0.12794 · weight (kg) - 27.82849, R2= .82. Our data indicate that similar LTM and UTM cardiorespiratory responses are achievable, and we provide a reasonable estimate of UTM VO2.  相似文献   

13.
To adhere to the principle of “exercise specificity” exercise testing should be completed using the same physical activity that is performed during exercise training. The present study was designed to assess whether aerobic step exercisers have a greater maximal oxygen consumption (max VO2) when tested using an activity specific, maximal step exercise test (SET; arms and legs) versus a maximal running test (legs only). Female aerobic step exercisers (N=18; 20.7 ± 1.5 years) performed three maximal graded exercise tests (GXTs): 2 SETs; 1 treadmill test (TMT). The SET consisted of six 3-min progressive stages of alternate lead, basic step, basic step with biceps curls, knee raise with pull-down, repeater knee with pull-down, lateral lunge with pull-down, and side squat with shoulder presses. Stepping rate was 32 steps· min?1 on an 8-in (20.32 cm) step for stages 1–3, and a 10-in (25.4 cm) step for stages 4–6. Submaximal and maximal heart rate (HR) and oxygen consumption (VO2) were recorded at the end of each stage. Test–retest reliability for the first five stages of the SET ranged from .91 to .97 for HR, and from .84 to .96 for VO2. Maximal HR was significantly greater (p =.0001) for the SET (200 ± 6.2 beats·min?1) as compared to the TMT (193 ± 7.9 beats·min?1). No significant difference was found for max VO2 (42.9 ± 8.5, 41.2 ± 5.9 ml·kg?1·min?1, p =.14). The SET was a valid and reliable protocol for assessing responses of these aerobic step exercisers; however, max VO2 from a TMT did not differ significantly from the SET. Conversely, max HR obtained from the criterion TMT was 7 beats·min?1 lower than from the SET. If a training HR for step exercise (arms and legs exercise) is prescribed based on the max HR from treadmill exercise (legs only), then the training HR should be calculated from a TMT max HR that has been increased by 7 beats·min?1 to obtain an intensity of step exercise comparable to that of running.  相似文献   

14.
Investigations in the 1990s evaluated the influence of breathing assemblies on respiratory variables at rest and during exercise; however, research on new models of breathing assemblies is lacking. This study compared metabolic gas analysis data from a mouthpiece with a noseclip (MOUTH) and a face mask (MASK). Volunteers (7 males, 7 females; 25.1 ± 2.7 years) completed two maximal treadmill tests within 1 week, one MOUTH and one MASK, in random order. The difference in maximal oxygen consumption (VO2max) between MOUTH (52.7 ± 11.3 ml · kg?1 · min?1) and MASK (52.2 ± 11.7 ml · kg?1 · min?1) was not significant (P = 0.53). Likewise, the mean MOUTH–MASK differences in minute ventilation (VE), fraction of expired oxygen (FEO2) and carbon dioxide (FECO2), respiration rate (RR), tidal volume (Vt), heart rate (HR), and rating of perceived exertion (RPE) at maximal and submaximal intensities were not significant (P > 0.05). Furthermore, there was no systematic bias in the error scores (r = ?0.13, P = 0.66), and 12 of the 14 participants had a VO2max difference of ≤3 ml · kg?1 · min?1 between conditions. Finally, there was no clear participant preference for using the MOUTH or MASK. Selection of MOUTH or MASK will not affect the participant’s gas exchange or breathing patterns.  相似文献   

15.
Exercise testing on motorised treadmills provides valuable information about running performance and metabolism; however, the impact of treadmill type on these tests has not been investigated. This study compared the energy demand of running on two laboratory treadmills: an HP Cosmos (C) and a Quinton (Q) model, with the latter having a 4.5 times stiffer running platform. Twelve experienced runners ran identical bouts on these treadmills at a range of four submaximal velocities (reported data is for the velocity that approximated 75–81% VO2max). The stiffer treadmill elicited higher oxygen consumption (C: 46.7 ± 3.8; Q: 50.1 ± 4.3 ml·kg?1 · min?1), energy expenditure (C: 16.0 ± 2.5; Q: 17.7 ± 2.9 kcal · min?1), carbohydrate oxidation (C: 9.6 ± 3.1; Q: 13.0 ± 3.9 kcal · min?1), heart rate (C: 155 ± 16; Q: 163 ± 16 beats · min?1) and rating of perceived exertion (C: 13.8 ± 1.2; Q: 14.7 ± 1.2), but lower fat oxidation (C: 6.4 ± 2.3; Q: 4.6 ± 2.5 kcal · min?1) (all analysis of variance treadmill comparisons P < 0.01). This study confirms that caution is required when comparing performance and metabolic results between different treadmills and suggests that treadmills will vary in their comparability to over-ground running depending on the running platform stiffness.  相似文献   

16.
Abstract

The purpose of this study was to develop a regression equation to predict maximal oxygen uptake (VO2max) based on nonexercise (N-EX) data. All participants (N= 100), ages 18–65 years, successfully completed a maximal graded exercise test (GXT) to assess VO2max (M= 39.96 mL·kg -1· min -1 , SD = 9.54). The N-EX data collected just before the maximal GXT included the participant's age; gender; body mass index (BMI); perceived functional ability (PFA) to walk, jog, or run given distances; and current physical activity (PA-R) level. Multiple linear regression generated the following N-EX prediction equation (R = .93, SEE = 3.45 mL·kg -1· min -1 , %SEE= 8.62): VO2max (mL·kg -1· min -1 ) = 48.0730 + (6.1779 x gender; women = 0, men = 1) – (0.2463 x age) – (0.6186 x BMI) + (0.7115 x PFA) + (0.6709 x PA-R). Cross validation using PRESS (predicted residual sum of squares) statistics revealed minimal shrinkage (R p = .91 and SEE p = 3.63 mL·kg -1· min -1 ); thus, this model should yield acceptable accuracy when applied to an independent sample of adults (ages 18–-65 years) with a similar cardiorespiratory fitness level. Based on standardized β-weights, the PFA variable (0.41) was the most effective at predicting VO2max followed by age (-0.34), gender (0.33), BMI (-0.27), and PA-R (0.16). This study provides a N-EX regression model that yields relatively accurate results and is a convenient way to predict VO2max in adult men and women.  相似文献   

17.
This study examined the separate and combined effects of heat acclimation and hand cooling on post-exercise cooling rates following bouts of exercise in the heat. Seventeen non-heat acclimated (NHA) males (mean ± SE; age, 23 ± 1 y; mass, 75.30 ± 2.27 kg; maximal oxygen consumption [VO2 max], 54.1 ± 1.3 ml·kg?1·min?1) completed 2 heat stress tests (HST) when NHA, then 10 days of heat acclimation, then 2 HST once heat acclimated (HA) in an environmental chamber (40°C; 40%RH). HSTs were 2 60-min bouts of treadmill exercise (45% VO2 max; 2% grade) each followed by 10 min of hand cooling (C) or no cooling (NC). Heat acclimation sessions were 90–240 min of treadmill or stationary bike exercise (60–80% VO2 max). Repeated measures ANOVA with Fishers LSD post hoc (α < 0.05) identified differences. When NHA, C (0.020 ± 0.003°C·min?1) had a greater cooling rate than NC (0.013 ± 0.003°C·min?1) (mean difference [95%CI]; 0.007°C [0.001,0.013], P = 0.035). Once HA, C (0.021 ± 0.002°C·min?1) was similar to NC (0.025 ± 0.002°C·min?1) (0.004°C [?0.003,0.011], P = 0.216). Hand cooling when HA (0.021 ± 0.002°C·min?1) was similar to when NHA (0.020 ± 0.003°C·min?1) (P = 0.77). In conclusion, when NHA, C provided greater cooling rates than NC. Once HA, C and NC provided similar cooling rates.  相似文献   

18.
Low energy availability, defined as low caloric intake relative to exercise energy expenditure, has been linked to endocrine alterations frequently observed in chronically energy-deficient exercising women. Our goal was to determine the endocrine effects of low energy availability in exercising men. Six exercising men (VO2peak: 49.3 ± 2.4 ml · kg?1 · min?1) underwent two conditions of low energy availability (15 kcal · kg?1 fat-free mass [FFM] · day?1) and two energy-balanced conditions (40 kcal · kg?1 FFM · day?1) in randomised order. During one low energy availability and one balanced condition, participants exercised to expend 15 kcal · kg?1 FFM · day?1; no exercise was conducted during the other two conditions. Metabolic hormones were assessed before and after each 4-day period. Following both low energy availability conditions, leptin (?53% to ?56%) and insulin (?34% to ?38%) were reduced (P < 0.05). Reductions in leptin and insulin were independent of whether low energy availability was attained with or without exercise (P > 0.80). Low energy availability did not significantly impact ghrelin, triiodothyronine, testosterone and IGF-1 (all P > 0.05). The observed reductions in leptin and insulin were in the same magnitude as changes previously reported in sedentary women. Further research is needed to understand why other metabolic hormones are more robust against low energy availability in exercising men than those in sedentary and exercising women.  相似文献   

19.
The purpose of this study was to develop an age-generalized regression model to predict maximal oxygen uptake (VO2max) based on a maximal treadmill graded exercise test (GXT; George, 1996) George, J. D. 1996. Alternative approach to maximal exercise testing and VO2max prediction in college students. Research Quarterly for Exercise and Sport, 67: 452–457. [Taylor & Francis Online], [Web of Science ®] , [Google Scholar]. Participants (N?=?100), ages 18–65 years, reached a maximal level of exertion (mean?±?standard deviation [SD]; maximal heart rate [HRmax]?=?185.2?±?12.4 beats per minute (bpm); maximal respiratory exchange ratio [RERmax]?=?1.18?±?0.05; maximal rating of perceived exertion (RPEmax)?=?19.1?±?0.7) during the GXT to assess VO2max (mean?±?SD; 40.24?±?9.11 mL·kg?1·min?1). Multiple linear regression generated the following prediction equation (R?=?.94, standard error of estimate [SEE]?=?3.18 mL·kg?1·min?1, %SEE?=?7.9): VO2max (mL·kg?1·min?1)?=?13.160?+?(3.314 × gender; females?=?0, males?=?1) ? (.131 × age) ? (.334 × body mass index (BMI))?+?(5.177 × treadmill speed; mph)?+?(1.315 × treadmill grade; %). Cross validation using predicted residual sum of squares (PRESS) statistics revealed minimal shrinkage (Rp ?=?.93 and SEE p ?=?3.40 mL·kg?1·min?1); consequently, this model should provide acceptable accuracy when it is applied to independent samples of comparable adults. Standardized β-weights indicate that treadmill speed (.583) was the most effective at predicting VO2max followed by treadmill grade (.356), age (?.197), gender (.183), and BMI (?.148). This study provides a relatively accurate regression model to predict VO2max in relatively fit men and women, ages 18–65 years, based on maximal exercise (treadmill speed and grade), biometric (BMI), and demographic (age and gender) data.  相似文献   

20.
Abstract

The purpose of this study was to compare the physiological responses of Nordic walking on a specially designed treadmill and Nordic walking on a level over-ground surface. Thirteen participants completed three 1-h Nordic walking training sessions. Following the training sessions, each participant performed two 1600-m over-ground Nordic walking trials at a self-selected pace. Each participant then completed two 1600-m Nordic walking treadmill trials on a Hammer Nordic Walking XTR Treadmill®, at the mean walking speed of their two over-ground Nordic walking trials. Breath-by-breath analysis of oxygen uptake ([Vdot]O2) and heart rate was performed during each trial. Caloric expenditure was calculated using the [Vdot]O2. Rating of perceived exertion (RPE) was assessed at the end of each trial. We found no significant differences in physiological variables collected during the two over-ground Nordic walking trials or the two treadmill Nordic walking trials. Mean walking speed was 106.96±11.49 m · min?1. Mean heart rate during treadmill walking (99±13 beats · min?1) was 22% lower than that during the over-ground condition (126±17 beats · min?1). Mean [Vdot]O2 and mean caloric expenditure were also lower during treadmill walking (15.18±3.81 ml · min?1 · kg?1, 0.08±0.02 kcal · min?1 · kg?1) than over-ground walking (24.16±4.89 ml · min?1 · kg?1, 0.12±0.02 kcal · min?1 · kg?1). Analysis of variance demonstrated that all variables were significantly higher during over-ground Nordic walking (P<0.001). A Mann-Whitney U-test demonstrated that the RPE for over-ground Nordic walking was greater than that for treadmill Nordic walking (P=0.02). Thus over-ground Nordic walking created a greater physiological stress than treadmill Nordic walking performed at the same speed and distance. The reason for this difference may have been the relatively narrow walking and poling decks on the treadmill, which made it difficult for the participants to place their poles correctly and maintain a consistent walking pattern. This would decrease the contribution of the arm muscles to overall oxygen consumption. In conclusion, the Hammer Nordic Walking XTR Treadmill® does not replicate the physiological stress of over-ground Nordic walking. Increasing the width of the decks could eliminate the discrepancy.  相似文献   

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